Writing of the Past Lights Up

A new technique involving light bulbs, cameras and computers is bringing back previously-lost words from ancient Sumerian clay tablets.

By Karl S. Kruszelnicki

While speaking is something that the most humans can do without any special instruction, writing is a fairly new technology that has to be taught.

Writing lets us circulate information widely and accurately. The earliest known form of writing, the so-called Sumerian cuneiform inscriptions, appeared about 5,000 years ago in what is today Southern Iraq. These clay tablets have become very badly eroded over the last five millennia - but a new technique involving light bulbs, cameras and computers is bringing back previously-lost words from the past.

Back then, the Babylonian Scribes would start off with a slab of wet clay, roughly the size of your hand. They would then write symbols on it with sharpened reeds, and let it dry. Writing with a slanted edge gave the straight lines a wedge shape - and in fact, "cuneiform" is a word made up from Latin and Middle French meaning "wedge-shaped".

In 1999, Bruce Zuckerman, the Director of the University of Southern California's West Semitic Research Project in Los Angeles, gave a lecture on how to recover the inscriptions on these badly-eroded clay tablets. He described how he had spent 20 years inventing new techniques using high-resolution photographs to read the cuneiform images. But in most cases, 5,000 years of erosion was just too much to overcome.

By a fortunate coincidence, Tom Malzbender had come to that lecture. Tom Malzbender, and his colleague Dan Gelb, worked at the Visual Computing Department of Hewlett-Packard Laboratories in Palo Alto, California. Tom had a remarkably simple technique to map the texture of rough surfaces and shove it into a computer so that you could explore the surfaces in a virtual world.

It's a remarkably simple low-tech device. He starts off with an opaque plastic half-dome, about a metre across. A digital camera is mounted at the top dead centre. Scattered all around the inside of the dome are 50 individual flash bulbs. First, one flash bulb switches on and illuminates the object, and then the digital camera takes a six-megapixel photograph - roughly three times better than your average domestic digital camera. And then that light bulb switches off and another one lights up, illuminating the object from a different angle - and the digital camera takes another six-megapixel photograph.

This process is repeated another 48 times for each of the individual flash bulbs. Each photo shows the object illuminated by a different light bulb from a different direction. The computer then does its stuff, and putting together all the information from the 50 individual photographs, constructs in its "mind" a virtual clay tablet. It works out where all of the surfaces on the object are, and at exactly what angle they're pointing.

Tom then improves his virtual clay tablet by telling the computer to coat it with an ultra-thin layer of bright shiny chrome. The reason for this is that the human eye is really good at picking up subtle changes in the shape of a surface, if the surface is very reflective. If you want proof of this, just look closely at the paint on the next shiny black car you see - every single defect stands out.

Finally, his computer invents a virtual spotlight and washes its beam of virtual light across the virtual chrome surface of his virtual clay tablet. The tiny bumps in the surface will reflect light only if the spotlight shines directly upon them. In fact, they can further enhance the surface of the virtual clay tablet with extra tricks - like pretending that there is a pinpoint spot of light between the walls of a scratch only a millimetre or so wide.

The results are absolutely astonishing. Details that were barely visible are now glaringly obvious. Walter Bodine is an expert in Babylonian writing based at Yale University, where they have 40,000 clay tablets in the Yale Babylonian collection. He had spent six years trying to work out exactly what was on one badly-eroded, but very interesting, clay tablet. But a few minutes with Tom Malzbender's new technology took them further than six years of painstaking deciphering and transcribing.

They could suddenly read that this 5,100-year-old clay tablet was a contract. Back in 3,100 BC, Ur Ningal, a Sumerian merchant, sold some slaves. The contract on this particular clay tablet gave a Money-Back Guarantee - if the slaves turned out to be faulty, the buyer could get a full refund.

This software and hardware is certain to find many uses. Zuckerman said, "We were even able to note the fingerprints of the scribe who held the clay while it was still wet". Well, if it can find 5,000-year-old fingerprints that nobody else had noticed, it might be able to find modern fingerprints at the scene of a crime.

This technology is certain to have other uses besides throwing a light on the past.